Method of stretching a filament



METHOD OF STRETCHING A FILAMENT Filed Nov. 6, 1951 /5 M 40 48 29 22 I232 llllllllllllll Invervtor: Lee E.D1Ll:s,

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2,736,344 METHUDDF STRETCHINGZA FIEAMENT Lee E. Dilts South Euclid; hio,assiguor to-General Elec-- tric Company, .a corporationof New York Aplic'ation Ndvember 6, 1951; Serial Nai-cssgrlr 3 Claims. 4017140 7116 Myinvention relates-to-a method andapparatus forestablishing adefinitepitchdnthe coiled-filament of an incandescent lampmount orthe-like, andmore particularly to a method and-apparatus forstretchingthefilament-by manipulating. or repositioning-the lead-inwires,

to which the filament. is connected, to provide-a uniformpitch,or'numbe'r of turns perunit length, of the-coil.

An object of my invention is to provide a novel methodand apparatus forestablishing a definiteand uniform pitch of the turns "ofacoiledfilament, especially a coiledcoil filament, of a completedmount,as for instance an incandescent lamp mount :of the type made by theapparatus disclosed Flaws Patent 2,085,578 dated June-- 29,'l937',andassigned to thesame assignee as the present invention. The method. is ofadvantage in compensating for differences in the manufacture of mountsresult ing in variations in tension and, accordingly, in spacing of theturns of the coiled filament thereof. These differences, for the mostpart, are caused by variation in the spacing of the lead-in wirestowhich the filaments I are attached, 'and are brought about by anon-uniform spacing of those portions of the lead-in wires embedded inthe vitreous stem of said mount and by non-uniform ties in tie wiresextending from an arbor ofthe stem to intermediate portions of thelead-in wiresr Accordingto the invention the portions of the lead-inwires extending beyond the vitreous stemof the mount are repositioned ordeformed in a manner to cause the extending or free end portions of saidleading-inwires, to which are con nected a coiled filament, to be spreadapart so that saidfilament is retained in a stretched condition and theturns thereof are spaced at definite distances.

Another object of my invention is to provide a method and apparatus foreffectively increasing the spacing between the ends of lead-in wires ofa mount, which method and apparatus are applicableto the repositioningof leadin wires which are connected at intermediate points to a fixedstem arbor by tie wires. The-method provides for the bending of thelead-in wires to effect the repositioning thereof in a manner to causerelatively little displacement of said lead-in wires at their points ofconnection to the tie wires and to widen the acute angle between saidlead-in wires to spread the ends thereof.

The method is also suited to the "establishment of a de-' sired tensionandcoilspacing'in a filament of a mount when a single lead-in wire atone end of the filament is repositioned in the manner described.

Further features and advantages of my invention will appear fromthe'following detailed description of species thereof and from theaccompanying drawing.

In the drawing, Fig. l is a side elevation of a device midway in theoperation of repositioning the lead-in wires of a mount to place afilamentconnected between said lead-in wires under predetermined tensionand the coils of said filament at a definite spacing;"Fig. Zi s aperspective view at substantially rightangles'to 1 showing the bending'and stop fingers'of the lead in wire reposi tionin'g device at theirlimit ofrnoveme'nt'with respect to a mount and showingitheoriginalposition of *said"lead"--- in-wiresin dot-dashlines; Fig.':3 is aperspective-viewyon Patented: Feb, .23 5

a smallerscale, of- -the -mount after separation' of the re---positioningdevice therefrom;-:Fi'gs-; 4 and 5 are planand-= back-viewsof the lead-in't'wire repositioning-device; and

Fig. 6 is a perspective view correspondingto Fig. 2 of a mountandmodifiedmeans for repositioning=the-1ead=in wire thereof As--bestseen-in-Figs;,-2 and3, the mount'6 comprises"' a glass stem-5 in whichare sealed'and 'anchored' 'a pair of" lead-in wires -:8 and 9 whichproject longitudinallyv therefromwn opposite-sides of *th'eaxis of the'stem 5."

A coiled-coil filament 12- is connected across 'the freeenlls' oflead-in-wires 8 and 9, and tie wires 10, 11' extend laterally outwardfrom an arbor 3 on stem -5 and have their ends looped loosely aroundintermediate portions of the "respective lead-in wires 8 and 9. Thefilament .12

is additionally supported by a support wire Iii-extending longitudinallyfrom =the-stem arbor? carries the conventional exhaust tube 4.

The stem 5 also" Thestretching*operation preferably takes'place' at aThe conveyor,--as herein represented by -thelead-in :wires S and 9 tostretch thefilament-12in accordancewith the invention.

The conveyor advances the mount'6 to a position directly over' thedevice 7 at a time when the stopfingers 14 and 15 in a retractedposition on one-side of the horizontal path of: movement .of the-mount6, and the bending'fingers 16 and 17 are located in a wide open positionon the opposite side of said path. The operation of the device 7 causesthe stop fingers 14 and 15 to be swung up to the operativeposition, atwhich theyare shown, by rotation of the hub 1 8-and the shaft 19-; andthe bending fingers or jaws 16and 17- are pivoted in a horizontal planeinto engagement with the outer sides of said lead-in wires 8 and 9 byrotation of the vertical shafts 26 and 21: Both operative movements ofthe device-'7 result from the timed operation of a portion of U the maindriving means (not shown) of the mount making apparatus, whichpo'rtionpreferablycorresponds to por tions actuating otherdevices thereof atother stations along the conveyor, and'which, at the described-momentinthe arrangement 'of the mount 6 before said device 7, causes anadvanceof theop'erat-irig bar 22'tothe left in Fig; l. Inasmuch as themain supporting body 23 of the device'7 is a stationary member mountedupon the upper end of the support column24fastened by bracket 25 to theframe of'the mountmaking apparatus, the mo,- tion of the operating bar22 swings the arm 26' on the lower'end of theshaft Zllt'o turn saidshaftZt).

The stop fingers14 and 15 are the firstelements of the device7 tobebroughtinto operative relation to the'mount 6 and, accordingly, areactuated by the first rotative movements of the shaft 20. During thisintervahthe shaft 20," to which is attached. a second arm 27 engaging aroller onpin 28 in the top surface of the slide 29, effects alongitudinal movement of said slide 29 in ways in the body 23 of thedevice 7, and also effects rotation of lever 31'by virtue of acorresponding motion ofthe push bar 30 extending from the end of theslide 29.' Thelever 31, 'in turn','jrotates the "arm 32"and' shaft 19thereby initiating the" swing of stop fingers 14 and 15 into op fnative-relation to the mount 6. The rotation of theshaft 20 occurs at atime when the push bar 39, which bears against a helical spring 33,extends out beyond the slide 29 to the limit set by the engagement ofpin 34 in the top of said push bar 30 with the end of a slot 35 in saidslide 29; and said rotation of shaft 20 does not disturb the position ofthe push bar 30 in the slide 29 or cause further compression of thespring 33 which is located behind said push bar 30 in an opening inslide 29 and is retained therein by the end plate 36 on said slide 29.The motion is transmitted from the push bar 30 and a pin 37 extendingtherefrom to the lever 31 which is pivoted on a pin 38 extending fromthe body 23 of the device 7, and from said lever 31 to a pin 39projecting from the arm 32. Bearings provided by the body 23 on oppositesides of the hub 18 supporting the stop fingers 14 and 15 establish thecenter of rotation of the shaft 19, the hub 18 and said stop fingers 14and 15. Said fingers 14 and 15 reach their limit of motion when the stopscrew 40 in a lug on the hub 18 seats against a projecting ear 41 onsaid body 23. This movement of the stop fingers '14 and 15 swings themup between the lead-in wires 8 and 9 to a position adjacent and underthe tie wires 10 and 11 and, in most instances, causes the outside edgesof said fingers 14 and 15 to bear against the lead-in wires 8 and 9inasmuch as said outside edges of the fingers are spaced slightlyfarther apart than the proximate sides of the loops in the ends of thetie wires 10 and 11.

The described rotation of the shaft 20 also causes the bending fingers16 and 17, on the opposite side of the mount 6 from stop fingers 14 and15, to close part way to the position shown in the drawing, and iscontinued until said bending fingers 16 and 17 have squeezed saidlead-in wires 8 and 3 closer together as shown in Fig. 2. The rotationof shaft 20 is transferred to the bending finger 16, which is pivotedupon an upper end portion of the shaft, through a yoke 44 which isclamped to said shaft 20. Said finger 16 is clamped between anadjustable screw 42 in one ear of said yoke 44 and a spring 43 held in awell in finger 16 and engaging the other ear of yoke 44. The rotation istransferred to bending finger 17, which is correspondingly pivoted uponthe upper end portion of a shaft 21, through a corresponding yoke 47,adjusting screw 45 and helical spring 46. Shafts 20 and 21 arejournalled in the body 23 of the device 7 and are rotated togetherthrough intermeshing of the spur gears 48 and 49 on the lower endportion of both shafts 20 and 21.

The function of the bending fingers 16 and 17 is to squeeze thoseportions of the lead-in wires 8 and 9 located between the stem tube andthe tie wires and 11 to thereby bend the wires 8 and 9 about the fixedfingers 14 and so that the free ends of said lead-in wires are spreadapart with concomitant stretching of the filament 12. This function ofthe device 7 corrects any variation in the form of the mount 6 caused byvariations in the spacing of the lead-in wires 8 and 9 within the stemtube 5 and such variations in said lead-in wires 8 and 9 and the tirewires 10 and 11 as may have been placed therein or may not have beencorrected during the prior mount making operations.

The bending fingers 16 and 17, as shown in Fig. 2, bend the lead-inwires 8 and 9 to a greater extent than is to be maintained in the finalmount 6 (Fig. 3) since some allowance must be provided for the springback in said lead-in wires 8 and 9 and for the contraction force of thecoiled-coil filament 12. The bends made in the leadin Wires 8 and 9 donot cause said wires 8 and 9 to move beyond the freedom allowed by theloops in the tie wires 10 and 11 and therefore do not result in anydirect pressure being applied to said loops, as would be the case if thesame operation were performed without the use of the stop fingers 14 and15. Symmetry in the bending of the lead-in wires 8 and 9 is attained bycausing the shafts and 21 to rotate until the adjacent or proximate earsof the yokes 44 and 47 thereon both bear against the post extending fromthe top of the body 23 of the device 7, so that all slack in the matingof the spur gears 48 and 49 is absorbed, and by adjusting the screws 42and 45 to effect the same motion in both of the bending fingers 16 and17 at such times.

During the final part of the rotation of the shaft 20 which effects thisclosing movement of the bending fingers 16 and 17, the motion of theslide 29 compresses the spring 33 behind the push bar 30 and causes thestop pin 34 in the latter to shift in the slot 35 in said slide 29. Thereverse rotation of the shaft 20 occurring when the device 7 is againdisengaged from the mount 6 causes the bending fingers 16 and 17 to moveaway from said mount 6 and then, as the pin 34 seats against the end ofthe slot 35 causes the stop fingers 14 and 15 to swing down and awayfrom the lead-in wires 8 and 9. On completion of these operations, allparts of the apparatus are out of contact with the mount 6, and thelead-in wires 8 and 9 and the filament 12 have sprung back part waytoward their original positions; however, the deformation of saidlead-in wires 8 and 9 causes them to bear against the inner, orproximate, sides the loops of the tie wires 10 and 11 and causes thefilament 12 to be retained under moderate tension. In the manufacture ofa mount for a -watt incandescent lamp, for example, it is customary tohave the filament stretched 1.5 mm. after the lead-in wirerespositioning operation is complete.

In a modification, illustrated in Fig. 6, the lead-in wires 8 and 9 areengaged at points above the tie wires 10 and 11 by relatively fixedfingers 51 and 52 at the outside of said lead-in wires. The lead-inwires 8 and 9 are engaged at points below the tie wires by relativelymovable bending fingers or jaws 53 and 54 located between the lead-inwires 8 and 9. After movement of the pairs of fingers 51, 52 and 53, 54to the positions shown in Fig. 6, the fingers 53, 54 are spread or movedapart to thereby spread the end portions of the lead-in wires 8 and 9and stretch the filament 12 a predetermined amount.

In both methods disclosed, the stop finger 14-15 and 51-52 protect theloops of the tie wires 10 and 11 from the pressure of the bendingfingers 1617 and 5354 respectively and result in the lead-in wires 8 and9 being repositioned so that the filament 12 is maintained in astretched condition designed to assist in causing the coils thereof tobe properly spaced.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

l. A method of stretching the coiled filament of an incandescent lampmount having a pair of lead-in wires anchored in and extendinglongitudinally from a stem, tie wires extending laterally from the sternand having their ends looped loosely about intermediate portions of thelead-in wires and the coiled filament connected between the ends of thelead-in wires, which method comprises holding the mount by its stem,bracing the lead-in wires against spreading at points adjacent to thetie wires and between the tie wires and said stern while applyingpressure to said lead-in wires at points on the opposite side of saidtie wires and in directions to spread apart the free ends of saidlead-in wires without distorting the loops in said tie wires and stretchsaid filament sufiiciently so that upon releasing the pressure theintermediate portions of the lead-in wires bear against adjacent edgesof the looped ends of the tie wires and the filament is retained in apredetermined stretched condition.

2. The method of forming an incandescent lamp mount having lead-in wiresanchored in and extending longitudinally from a stem and having tiewires extending laterally from said stern toward intermediate portionsof the lead-in wires which method comprises preliminarily connecting acoiled filament between and across the free ends of said lead-in wiresand forming the ends of said tie wires into loops loosely encircling thesaid intermediate portions of the lead-in wires, and then stretching thefilament, while holding the mount by its stem, by engaging each of thelead-in wires at points adjacent to and on opposite sides of the tiewire and applying pressure thereto in directions to cause the portionsof the lead-in wires between their points of emergence from the stem andthe tie wires to be bent closer together and the extremeties of saidlead-in wires to be spread apart so as to effect a spreading apart ofthe free ends of the lead-in wires and concomitant stretching of thefilament sufficient so that upon removal of the pressure the lead-inwires are held by contraction of the filament against the inner sides ofthe loops in said tie wires.

3. The method of forming an incandescent lamp mount having lead-in wiresanchored in and extending longitudinally from a stem and having tiewires extending laterally from said stem toward intermediate portions ofthe lead-in wires which method comprises preliminarily connecting acoiled filament between and across the free ends of said lead-in wiresand forming the ends of said tie wires into loops loosely encircling thesaid intermediate portions of the lead-in wires, and then stretching thefilament, while holding the mount by its stem, by bracing the lead-inwires against movement toward each other at points adjacent to the tiewires and between the tie wires and the said free ends of the lead-inwires while applying pressure to said lead-in wires at points on theopposite sides of said tie wires and in directions to squeeze thelead-in wires toward each other to cause the said free ends of thelead-in wires to be spread apart without distorting the loops in the tiewires and to cause the filament to be stretched sufficiently so thatupon removal of the pressure the lead-in wires are held by contractionof the filament against the inner sides of the loops in said tie wires.

References Cited in the file of this patent UNITED STATES PATENTS1,733,881 Illingworth Oct. 29, 1929 2,085,578 Flaws June 29, 19372,145,911 Anderson Feb. 7, 1939 2,575,771 Russell Nov. 20, 1951

